Chemical Constituents From Ocimum Basilicum L.and Their Bioactivities

Ocimum basilicum L.（Basil）is an annual herb in the family of Lamiaceae,and has been used as flavouring and consumed medicinally in China for more than 2 000 years.Basil is rich in volatile oils,flavonoids,terpenoids,phenylpropanoids and sterols,polysaccharides and fatty acid compounds.Modern pharmacological activity studies have shown that basil has a wide range pharmacological effects of mosquito repellent,anti-inflammatory,antioxidant,antibacterial,anticoagulant,hypoglycemic,hypolipemic,antihypertensive and anti-cancer etc.Tracing antioxidant and hypoglycemic natural substances from herb medicinal plants is one direction in our lab.We carried out a bioassay guided systematical isolation to find the active substance basis of fresh arieal extraction part of basil in blooming stage.The essential oil and hydrosol were extracted by steam distillation.The residue was extracted by ethanol and extracted by ethyl acetate.The extraction fraction of ethyl acetate was segmitated and subdivided by silica gel,octadecyl bonded silica gel（ODS）,sephadex LH-20,MCI CHP20P gel column chromatography and RP-HPLC preparative chromatography.The pure compounds were elucidated by extensive 1D-and 2D-NMR spectra and mass spectrum,and compared with the reported data in literature.Finally,total of 32 compounds were isolated and identified from basil extraction,including two new compounds,namely tournefolic acid B methyl ester（6,JOB-41）and 2α,3β,24,29-tetrahydroxy-olean-12-ene-28-acid-29-O-β-D-glucopyranoside（17,JOB-39）.The remaining structures are methyl cinnamate（1,JLL-1）,（1R,2S,3S,4R）-dimethyl-3,4-diphenylcyclobutane-1,2-dicarboxylate（2,JOB-3）,（1R,2S,3R,4S）-dimethyl-3,4-diphenylcyclobutane-1,2-dicarboxylate（3,ZJZ-2）,ferulic acid（4,JOB-36）,rosmarinic acid（5,JOB-21）,salvianolic acid N（7,JOB-22）,gardenin B（8,JOB-4）,5,7-dihydroxy-6,8,4’-trimethoxyflavone（9,JOB-10）,oleanolic acid（10,JOB-9a）,maslinic acid（11;JOB-12）,3-epimaslinic acid（12,JOB-28）,hyptatic acid A（2α,3β,24-trihydrxyolean-12-en-28-oic acid,13,JOB-23）,3-epihyptatic acid A（2α,3α,24-trihydrxyolean-12-en-28-oic acid,14,JOB-31）,arjunolic acid（15,JOB-11a）,2α,3α,19α,24-tetrahydrxyolean-12-en-28-oic acid（16,JOB-35）,2α,3β,19α-trihydroxyolean-12-en-24,28-dioic acid-28-O-β-D-glucopyranoside（18,JOB-43）,ursolic acid（19,JOB-9b）,corosolic acid（20,JOB-13）,2α,3β,24-trihydroxyurs-12-en-28-oic acid（21,JOB-27）,2α,3α,24-trihydroxyurs-12-en-28-oic acid（22,JOB-32）,2α,3β,24-trihydroxyurs-12,20（30）-dien-oic acid（23,JOB-30）,pomolic acid（24,JOB-24）,tormentic acid（25,JOB-11b）,hyptatic acid B（2α,3β,19α,24-tetrahydroxyurs-12-en-28-oic acid,26,JOB-25）,2α,3α,19α,24-tetrahydroxyurs-12-en-28-oic acid（27,JOB-34）,2α,3β,19α-trihydroxyurs-12-en-24,28-dioic acid-28-O-β-D-glucopyranoside（28,JOB-40）,Chestnoside B（29;JOB-42）,betulin（30,JOB-7）,betulinic acid（31,JOB-8）,alphitolic acid（32,JOB-29）.Compounds 2-3,7-9,12-14,16,18,21-23,25-30 and 32 were isolated from basil for the first time.DPPH scavenging experiments were carried out on basil extract and ethyl acetate segment.Among them,ethyl acetate segment（OBE-8）showed high activity.Among twenty-seven basil monomer compounds,four phenolic acids（4-7）isolated from OBE-8showed significant scavenging activities,with EC₅₀values ranging from 9.92 to 24.43μg/m L,and compound 5 was equivalent to Trolox(EC₅₀=10.07μg/m L).Two phenolic acid and eleven phenylpropanoid compounds were showedα-glucosidase inhibitory activity,with IC₅₀values ranging from 1.85 to 24.09μg/m L,comparing with the IC₅₀value of 2.97 ng/m L of acarose.Among them,compounds 6,10,19,20,29,30,31 were showed higher activity with IC₅₀values ranging from 1.85 to 5.95μg/m L.Bioactivity studies showed that phenolic acids in basil had high antioxidant activity and pentacyclic triterpenoids had good hypoglycemic activity.The new compound 6 and compound 7 showed both DPPH scavenging ability andα-glucosidase inhibitory activity.This indicates that basil has potential development value in anti-aging,hypoglycemic health food and cosmetics.